Colored photoresist materials have been generally known in the art for many years. The most common use has been for color proofing applications. See, for example, U.S. Pat. Nos. 3,671,236; 4,596,757; 4,650,738; 4,656,114; 4,659,642; 4,751,166; 4,772,533; 4,808,508; 4,929,532; 4,948,693; and 5,248,583 (each describe a photosensitive color element comprising a permanent adhesive layer); U.S. Pat. No. 5,213,941 (describes a photosensitive color element comprising a partially developable adhesive layer); U.S. Pat. No. 3,884,693 (describes a photosensitive color layer on a releasable carrier); U.S. Pat. Nos. 4,260,673; and 4,482,625 (describe a photosensitive color layer on a releasable carrier and process of transferring the aqueous developed image onto a photopolymerizable receiving layer); European Application 621322 A1 (describes an aqueous developable macromolecular dye photoresist comprising a carrier and colored photoresist layer) and U.S. Patent Nos. 4,571,374; 4,672,020; 4,756,988 (describe a photoresist which may contain a colorant and an adjacent developable adhesive layer.).
The use of colored photoresist materials for the preparation of color filter arrays are also known. In U.S. Pat. No. 4,877,697, the preparation of a color filter array is described using color proofing films. Either a positive or a negative acting photoresist comprising a temporary support, an oxygen barrier or release layer, a colored photoresist layer and a permanent adhesive layer is laminated to a substrate and the temporary carrier removed. The photoresist is imagewise exposed with actinic radiation and then developed with an alkali developer leaving behind the image and the adhesive layer. The process is then repeated for each of the desired colors. Since the adhesive layer is a permanent part of the construction, the colored images are separated by interposing adhesive layers. The adhesive layers cause the different colored images to be on different planes and increase the thickness of the overall construction, often exceeding 10 microns in thickness. For optimal performance in a LCD color filter, it is desirable for the different colored images to lie in the same plane or at least within a thickness of 3 microns. The presence of the clear adhesive layers and color layers on different planes farther away from the black matrix can lead to unwanted leakage of projection light and cause optical distortions of the image. In addition, entrapment of air during the lamination process can cause unwanted voids or pinholes and inadequate adhesion of the color elements to the substrate.
The preparation of color filter arrays using photoresists that do not contain a permanent adhesive layer are also known. For example, in U.S. Pat. No. 4,777,117, the preparation of a color filter array is described using either a positive or negative acting photoresist and a special photomask with a registration mark. In U.S. Pat. No. 5,292,613, a process is disclosed for preparing a color filter array on glass using an article comprising a temporary support, a thermoplastic layer, an optional oxygen impermeable layer and a light sensitive layer. The image is formed by laminating the light sensitive layer to the substrate, removing the support and the thermoplastic layer, exposing with actinic radiation, and developing the image with a developer solution. A similar construction is described in U.S. Pat. No. 5,294,516; except the thermoplastic layer in this construction is alkali soluble and remains with the photosensitive layer when transferred to a substrate. The absence of an adhesive in these type of constructions cause poor transfer or adhesion of the image when dust, entrapped air or other surface irregularities are present.
In JP 05127016 A, a process for producing a color filter array is described using a dry peel apart development process. A photosensitive color element comprising a temporary support and a photosensitive color layer is laminated to a transparent substrate, imagewise exposed to actinic radiation and developed by peeling apart the construction. The image resolution of systems of this type are typically not as good as solvent or aqueous developed systems.
Even though it is highly desirable to eliminate the adhesive layer in colored photoresist materials for use in color filter array applications, a concern for contamination of the colored images arises due to the migration of materials during the lamination and development process steps of subsequent colors.